ABS Pump Motor !

glad your on the mend ALEX
http://shop.ebay.co.uk/i.html?…c=bmw+abs+punp+e31&_rdc=1

For the 840, I found the ABS pumps on ebay ending with part number xxxxx10, whilst the ETK says it should be xxxxx11, but I'm sure the actual motor parts are all the same.

By the way, the location of the ABS pump is probbly the worst location the designers could have found for it. It is directly beneath the headlight cutouts on the bonnet and right in front of the wheels, protected only by a plastic wheelarch liner that's prone to cracking. It may be a good idea to give the new motor some protection with a good coating of wax and to make a splash cover for the unit out of thin zinc sheet or similar.

I may have this problem too (or 2 front wheel sensors -which Im looking for used), how did your mechanic determine this was the issue?

Does anyone know if the motor can be removed from the pump housing in-situ ('93 850CSi)?

mat,

Your CSI will probably habve the older pump design- the one with the plactic cover that houses the relays beneath it. It may be possible to remove the motor, leaving the rest in situ. There was a post on this forum some time back of some who'd done just that.

if you have intermittent faults, check the wiring and connectors carefully, first. Wheel sensors are extremely expensive at around £170 each and I think the dessign is exclusive to the e31.

Zitat von arnie;83926

if you have intermittent faults, check the wiring and connectors carefully, first. Wheel sensors are extremely expensive at around £170 each and I think the dessign is exclusive to the e31.

Not to derail this thread, but any idea what resistance should be reading on the sensors?

I had 3 faults read by AutoBoss, both front sensors and the ABS Pump relay. I changed both the relays today (as you mention its the older design, relays on pump) and it worked, then stopped again, then started to work more consistently again, dunno what it will do tomorrow if I try it. It "may" be fine.

Well, a brand-new sensor that I have reads 997ohms, so I guess the nominal reading should be 1kohm.

However, if there is dirt on the sensor, it may not give a signal, even though its resistance is OK. The sensors have a built-in magnet, whose magnetic field (flux) is modulated by the steel teeth on the wheel rotor and the changing field then produces a varying voltage in the sensor coil. Hence, if the magnetic flux is blocked by metal debris, the sensor may not work.

Not meant as a criticism, but I saw the one that you probably bought off ebay. It's inevitably going to be as old or older than yours, so don't assume it will be perfect inside the motor (the aluminium valve-block looked quite pitted and corroded, but the motor part didn't appear too bad, so it may be OK.)

However, if the motor magnets are still well attached to the motor stator, I would suggest a good internal clean with a degreaser and then to spray coat the magnets with a laquer to seal against moisture and further corrosion. An electrical varnish would be best, but you can use a clear acrylic from Halfords etc and bake in an oven at 80c for an hour (lowest setting). Actually, probably good to give it a bake before coating it to dry out any moisture first.

Also, be sure to clean the brushes and commutator with very fine wet/dry 1000 grit paper.

If you want, you can also treat the rotor armature to a lacquer coating, but obviously not on the commutator ring.

I also bought one off ebay (£19!) so I could dismantle it and salvage parts.
However.. touch wood.. after driving around on it with the "new" (also as old actually, from a scrap E34) ABS Relays in it it seems to be working fine, no lights on the dash till it actually is slipping.

Incidentially the 6pin ABS Relay from the E34 needs the plastic key snipped off and the unit rotated 180 degrees to fit the E31, they are one part number apart and identical otherwise.